The present invention relates to a magnetic resonance imaging apparatus that carries out a pulse sequence in synchronization with a biosignal.
As methods for acquiring an image of a blood flow in the abdomen of a subject, respiratory gating method and heart rate gating method are known. In the respiratory gating method, a pulse sequence is carried out in synchronization with respiration signals. In the heart rate gating method, a pulse sequence is carried out in synchronization with heart rate signals. (See, e.g., Japanese Unexamined Patent Application Publication No. 2008-148806 and Japanese Unexamined Patent Application Publication No. 2010-220859.)
In the respiratory gating method, the respiration of a subject is detected and the timing with which a pulse sequence is carried out is determined so that data can be acquired during a period for which body motion arising from respiration is small. However, if the respiration of a subject becomes irregular during scanning, data cannot be acquired during a period for which the body motion is small and the image quality may be degraded.
In the heart rate gating method, the heart rate of a subject is detected and the timing with which a pulse sequence is carried out is determined so that data can be acquired during a desired period of cardiac phase (for example, diastole). However, if the heart rate becomes irregular because of such a cause as arrhythmia during scanning, data cannot be acquired during a desired period of cardiac phase and the image quality may be similarly degraded.
Therefore, an image whose quality is not degraded so much even though the respiration or heart rate of a subject becomes irregular during scanning is desired.